Hohervalente Derivate der d‐Metall‐Sauren, 13. Homoscorpionate als tripodale Ankerliganden chlorfunktioneller Oxo‐ und Imidokomplexe von Elementen der 5.‐7. Gruppe

Abstract

Higher‐Valent Derivatives of the d‐Metal Acids, 13. — Homoscorpionates as Tripodal Anchoring Ligands of Chloro Functionalized Oxo and Imido Complexes of Elements of Group 5–7 Hydridotris(pyrazolyl)borate complexes of elements of group 5–7 have been prepared by reaction of d0‐metalloyl chlorides [M(Y)nClm]x (Y = O, NR) with KTp* (Tp* = κ3‐HB(3,5‐Me2pz)3). Thus [NbOCl3]x and [TaOCl3]x are converted into monomeric and well‐characterized oxo complexes [Tp* Nb(O)Cl2] (1) and [Tp*Ta(O)Cl2] (2). In a similar way [Tp* Mo(O)2Cl] (3) and [Tp*W(O)2Cl] (4) have been obtained from the oxo chlorides [MoO2Cl2]x and [WO2Cl2]x, respectively. tert‐Butylamine reacts with NbCl5 and TaCl5 in the presence of pyridine to give the imido pyridine complexes [Nb(NtBu)Cl3(py)2] (5) and [Ta(NtBu)Cl3(py)2] (6) in excellent yield. Imido complexes [Tp*V(NtBu)Cl2] (7), [Tp* Nb(NtBu)Cl2] (8), and [Tp*Ta(NtBu)Cl2] (9) are formed by the reaction of KTp* with the precursers [V(NtBu)Cl3]x or 5 and 6, respectively. The corresponding imido complexes of group 6, namely [Tp*Cr(NtBu)2Cl] (10), [Tp*Mo(NtBu)2Cl] (11), and [Tp*W(NR)2Cl] (R = tBu 12a, 2,4,6‐Mesityl 12b, SO2Ph 12c) are obtained directly from the imidoyl chlorides or their complexes with Lewis bases. 11 and 12 are prone to protonation at the imido ligand to yield cationic amido species [Tp*M(NtBu)(NHtBu)Cl]BF4 (M = Mo 13, W 14). Finally the preparation of cationic imido rhenium complex [Tp*Re(NtBu)2Cl]PF6 (15), isoelectronic with 10–12, is described. The molecular structure of 11 has been determined by X‐ray diffraction. Despite of a maximum electron count of 20 valence electrons, all three pyrazolyl groups of the tripodal ligand are facially coordinated. In a way similar to the well‐known ring slippage of analogous cyclopentadienyl complexes, the weakest bound pyrazolyl ligand is asymmetrically attached to molybdenum deviating from the positions expected for local C3v symmetry.

Sandwich and Half‐Sandwich (Imido)niobium Complexes

“…[32,33] The synthesis of [Nb(ϭNtBu)Cl 3 (py) 2 ] was reported by Sundermeyer et al [34] These complexes have been employed in the synthesis of the cyclopentadienyl-containing niobium complexes discussed hereafter.…”

Plasma-Assisted MOCVD Growth of Superconducting NbN Thin Films Using Nb Dialkylamide and Nb Alkylimide Precursors

“…via a syringe. The reaction mixture was warmed to room temperature, and refluxed for 2 h. The resultant solution was then added via a cannula to a suspension of Cl 3 Nb=N t Bu(py) 2 [28] (0.037 mol) in 150 mL Et 2 O, precooled to ±78 C. The resulting brown suspension was next warmed to 78 C and stirred for an additional 12 h. Volatiles were removed in vacuo, and the crude product extracted with pentane (3 50 mL) and filtered through a glass frit under N 2 into a Schlenk flask. The pentane was removed in vacuo, and pure 2b obtained via sublimation (90 C/10 ±4 torr) as a pale-yellow solid.…”

Synthesis and characterization of poly(pyrazolyl)borate tantalum amide complexes and their reactivities toward oxygen

“…Although numerous studies have been conducted on polypyrazolyborate complexes of main group and transition metals, only a few studies of Ta complexes containing the ligands are known [8][9][10][11][12][13][14][15][16][17][18] . Notably, no Ta complex containing only polypyrazolyborate and amides has been reported.…”